When Little Disorder Could Be a Good Thing for Lithium Batteries

An MIT battery with the disordered cathode was able to maintain an energy density of 660 watt-hours per kilogram.

Published: 22-Jan-2014

odern technology demands more and more power, lithium-ion batteries have been getting increasingly dense. There hasn’t been a true breakthrough in battery technology recently, so scientists have been working on ways to fit more components inside the same space. That means very precise work to keep everything neat and tidy.

Now a team of researchers from MIT is pointing out some disorder could be a good thing in lithium-ion batteries.

One of the issues engineers have had to contend with when layering battery components was that the materials might not hold up and could blend together. Lithium ions are less able to move through such muddled layers of cathode. This was seen as a universally bad thing — a failed design that would quickly lose capacity.

However, the MIT team found something remarkable when working with a combination of lithium, chromium, and molybdenum for the cathode. The design alternated between lithium and each of the transition metals in layers, which according to conventional wisdom, would result in the cathode blending together. And indeed, after 10 cycles the team checked out the innards with an electron microscope to find them quite messy. Bizarrely, the cell still worked fine.

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